Abstract: In a wireless communication system, a transmission device includes: a generation section configured to encrypt information shared between the transmission device and a reception device using first encryption information which changes in accordance with the sequence information, and to generate encrypted data for the shared information; a transmission section configured to transmit, to the reception device, the encrypted data for the shared information; a reception section configured to receive, from the reception device, information about a result of a comparison between the shared information and a result of decrypting the encrypted data for the shared information using second encryption information which changes in accordance with the sequence information assigned to the encrypted ciphering-process-target data at the reception device; and a determination section configured to determine, based on the comparison result, whether the first and second encryption information matches or not.